Learning is a complex, dynamic process, structured from motor and perception skills which, when cortically processed, give rise to cognition. Disorders in specific areas of the central nervous system connected to notions of bodily schemes, space, and time, constitute the neuropathologic basis for perceptomotor alterations and sensations disorders that may result in learning impairments1.

One-hundred and three children with and without learning disorders were enrolled in this study. Sixty (58.2%) children did not report learning disorders and 43 (41.7%) reported difficulties at school2.

Genetic factors, peripheral sensorial disease, neurogenic infirmities, diseases in general, social and cultural handicap, and learning disorders may negatively impact performance at school3.

Alterations in basic function integration, bodily schemes, spatial orientation, rhythm, fine motor coordination, laterality, analysis and synthesis functions, integration of parts into a whole, symbolization, language and its many aspects, impulse, attention and memory are neurogenic disorders that may produce learning impairment4.

Static balance is an important neurological function for the maintenance of postures adequate for learning. Dynamic balance is also an important evolutional function that provides insights on neurological maturity. Reports in the literature indicate that children with less developed function in this area have increased probability of having learning difficulties5.

The vestibular system, the proprioceptors, and the cerebellum are responsible for functions such as muscle tone, posture, balance, eye-motor coordination, and spatial orientation. This system seems to be largely involved in school learning processes6.

Narciso et al.7 looked at vestibular variations in children and observed that 47% of the subjects had complaints related to performance at school. They found that vestibular disorders may be associated with learning and motor impairments.

According to Campos et al.8 infantile vestibular disorder may considerably affect communication skills, psychological status, and performance at school. Low performance at school may also be indicative of labyrinthine disease.

Caovilla et al.9 found that early identification of infantile vestibular disease and etiologic treatment are of paramount importance in preventing the complications that frequently involve motor development and language acquisition. Vestibular tests should be done in every child suspected for vestibular disorder, although it is not easy to obtain precise accounts of the symptoms from the parents or the child.

Functional vestibular tests can be done through electronystagmography and vectonystagmography. Digital vectonystagmography is one of the most widely employed tests in our practice to assess vestibular function, as it offers increased diagnostic sensitivity by measuring parameters connected to vestibular-eye-motor function and comparing stimuli to responses, apart from identifying the direction of the phenomena10.

Ganança et al.11 studied 30 children with poor performance at school and found alterations under computerized nystagmography in 20.0% of the subjects.

According to Caovilla et al.12 the tests included in digital vectonystagmography are eye-motor (eye motion, spontaneous and semi-spontaneous nystagmus, saccadic movement, and optokinetic nystagmus) and vestibular tests (rotational and thermal stimulation).

Abnormalities in voluntary saccadic control have been observed in many development disorders such as: dyslexia; learning impairments; attention deficit and hyperactivity disorder13.

Eye motion patterns manifested during reading require alternation between saccade and fixation. It starts off with saccade covering 8 to 10 words combined with eye fixation and ends with prolonged saccade to restart reading another line14.

The saccadic pathway involves various regions of the cerebral cortex, cerebellum, and brainstem. Parameters such as latency, velocity, and accuracy of saccadic movements can be used to assess how effectively the central nervous system (CNS) manages rapid eye movement. Few CNS disorders remain undetected when latency, velocity, and accuracy of saccadic movement is rigorously measured10.

Vestibular alterations found in dyslexic children have led authors Frank and Levinson15 to postulate that vestibular disorders and spontaneous nystagmus may interfere with sequential eye fixation required for reading.

Pendulum tracking is another type of eye motion that results from looking at a moving target used to assess the integrity of the eye-motor system in controlling slow eye motion, as they are affected by CNS and vestibular system disorders.

Following the teacher move around in the classroom, copying from the blackboard, reading, writing, and focusing require good eye-motor function and unaffected vestibular interconnections.

Optokinetic nystagmus is a rhythmic involuntary unconscious automatic ocular phenomenon. It may be reproduced when patients are asked to follow dots that move back and forth in opposite directions. It is an exteroceptive response that compensates the movement of the environment through psycho-optical impulses. Optokinetic nystagmus may be altered in CNS syndromes and vestibular disorders10.

Horak et al.16 analyzed vestibular function in children with and without reading and writing impairment and found alterations in the vestibulo-ocular reflex in 20% of the subjects with poor performance at school, and that 7% of the children without impairments had vestibular alterations.

The rotational stimulation produced in the decreasing rotational pendulum test allows the assessment of labyrinthine compensation status and its directional preponderance17.

Ayres18 looked at nystagmic movements in post-rotational stimulation in children with learning impairments and saw reduced post-rotational nystagmus in 50% of the children with learning impairment and exacerbated post-rotational nystagmus in 13% of them.

Thermal stimulation done in caloric tests is the most sensitive of conventional vestibular tests done in patients without specific complaints or anomalies in other vestibular assessment steps.

Ganança et al.11 studied 30 children with poor performance at school and found alterations under computerized nystagmography in 20.0% of the subjects, all in peripheral topographic diagnosis. According to the authors, most alterations were seen in the caloric test.

Ganança19 conducted a study with 64 children affected by language disorders without complaints of dizziness and found increased rates of vestibular alteration in the peripheral topographic diagnosis.

Relevant findings were observed in the studies by Franco and Caetanelli20. Computerized vectonystagmography was performed in school-aged children and 20.7% of the subjects were found to have unilateral and bilateral peripheral irritative vestibular disorders.

Sensorial stimulation is fundamental for the development of language in children. When stimulated from an early age, children develop good coordination and focus. They also develop their creativity and self-confidence, and improve the chances of not having learning disorders.

This study aimed at analyzing vestibular function in school-aged children underperforming at school to better understand the triggering vestibular disorders and to consequently allow the development of future studies that address early intervention.

Table 1 shows the distribution of the sample in relation to gender and school performance.

Table 2 shows the results of Student”s t-test controlled by Lavene”s test for Equality of Variances so as to check the possible differences between the means of parametric variables for eye-motor calibration parameters, namely latency, velocity, and accuracy.

Figure 1 features a box plot containing the statistical analysis for eye-motor calibration parameter latency.

Figure 1.

Box plot for right and left calibration eye-motor parameter (latency) per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.04MB).

Figure 2 features a box plot containing the statistical analysis for eye-motor calibration parameter velocity.

Figure 2.

Box plot for right and left calibration eye-motor parameter (velocity) per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.04MB).

Figure 3 features a box plot containing the statistical analysis for eye-motor calibration parameter accuracy.

Figure 3.

Box plot for right and left calibration eye-motor parameter (accuracy) per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.04MB).

Table 3 shows the results for Student”s t-test controlled by Levene”s test for Equality of Variances so as to check for possible differences between means of parametric variables for saccadic movement eye-motor parameters latency, velocity, and accuracy.

Figure 4 features a box plot containing the statistical analysis for saccadic movement eye-motor parameter latency.

Figure 4.

Box plot for right and left saccadic movement eye-motor parameter (latency) per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.04MB).

Figure 5 features a box plot containing the statistical analysis for saccadic movement eye-motor parameter velocity.

Figure 5.

Box plot for right and left saccadic movement eye-motor parameter (velocity) per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.04MB).

Figure 6 features a box plot containing the statistical analysis for saccadic movement eye-motor parameter accuracy.

Figure 6.

Box plot for right and left saccadic movement eye-motor parameter (accuracy) per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.04MB).

Table 4 shows the results for Student”s t-test controlled by Levene”s test for Equality of Variances so as to check for possible differences between means of parametric variables for gains in pendulum tracking at 20Hz, 40Hz, and 80Hz.

Figure 7 features a box plot containing the statistical analysis for gains in pendulum tracking at 20Hz, 40Hz, and 80Hz

Figure 7.

Box plot for parameter gain in pendulum tracking at 20Hz, 40Hz, and 80Hz per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.04MB).

Table 5 shows the results for Student”s t-test controlled by Levene”s test for Equality of Variances so as to check for possible differences between means of parametric variables nystagmus directional preponderance (NDP) in the optokinetic test.

Figure 8 features a box plot containing the statistical analysis for nystagmus directional preponderance (NDP) in the optokinetic test.

Figure 8.

Box plot for nystagmus directional preponderance (NDP) in optokinetic tests per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.03MB).

Table 6 shows the results for Student”s t-test controlled by Levene”s test for Equality of Variances so as to check for possible differences between means of nystagmus directional preponderance (NDP) in decreasing rotational pendulum test (DRPT) for lateral (NDP L), posterior (NDP P), and superior semicircular canals (NDP S).

Figure 9 features a box plot containing the statistical analysis for nystagmus directional preponderance (NDP) in the decreasing rotational pendulum test (DRPT) for lateral (NDP L), posterior (NDP P), and superior semicircular canals (NDP S).

Figure 9.

features a box plot containing the statistical analysis for nystagmus directional preponderance (NDP) in the decreasing rotational pendulum test (DRPT) for lateral (NDP L), posterior (NDP P), and superior semicircular canals (NDP S).

(0.04MB).

Table 7 shows the results for Student”s t-test controlled by Levene”s test for Equality of Variances so as to check for possible differences between means of parametric variables for nystagmus slow component angular velocity (SCAV) in the caloric test, at 42ºC and 18ºC for both ears.

Figure 10 features a box plot containing the statistical analysis for nystagmus slow component angular velocity (SCAV) in the caloric test at 42ºC and 18ºC for both ears.

Figure 10.

Box plot for right and left caloric tests (CT) at 18ºC and 42ºC per group. (Student”s t-test controlled by Lavene”s test for Equality of Variances between the means of parametric variables of interest).

(0.04MB).

Table 8 shows the distribution of the sample in relation to final diagnosis and school performance. Mann-Whitney”s test was used to assess differences and elicit the statistically significant relationship between the analyzed variables (p<0.001).

In our results we could verify the distribution of the sample in percent terms of school performance in relation to gender. Some similarity was observed (p= 0.121) between the analyzed variables, and no significant differences were seen between genders.

Forty-five (51.0%) of the 88 children included in the study did not report any difficulties at school, whereas 43 (49.0%) were underperforming.

Similar findings were reported by Farias et al.2 in a study that looked at 103 children with and without difficulties at school, 58.2% of whom did not report impairment and 41,7% did. Narciso et al.7 analyzed vestibular disorders in children and saw that 47% of them complained of low performance at school.

The remarks made by Schachter et al.3 and Sandler4 should be taken into account. In their studies they found that learning can be affected by genetic factors, peripheral sensorial conditions, and neurogenic diseases, among others. Within neurogenic disorders lie the conditions involving basic functional integration of the bodily scheme and or spatial orientation.

According to Guardiola et al.5, static and dynamic balance are important neurologic functions that enable children to adopt proper postures for learning. The authors claim that children with underdeveloped function in this area have an increased likelihood of experiencing learning difficulties.

Many are the contributions given by the studies done by Capovilla et al.6 and Campos et al.8 on the associations between the vestibular system and learning performance. Vestibular disorders in children may considerably impair their communication skills, psychological status, and school performance; the latter is a valuable indicative of labyrinthine disease.

According to Tuma et al.10, digital vectonystagmography is one of the most widely employed methods to assess vestibular function, as it grants additional diagnostic sensitivity by allowing the measurement of parameters connected to vestibular and eye-motor function and comparison between stimuli and responses, apart from identifying the direction in which such phenomena occur.

Our study found that the mean values associated with eye-motor parameters, both in the calibration of eye and saccadic movement, are within normal ranges for digital vectonystagmography according to Ganança et al.24 for latency, velocity, and accuracy. However, a statistically significant association was observed in the mean values for accuracy (p=0.043) in saccadic movement when comparing children underperforming at school to those doing well in class. Significance was found in only one parameter to the right side.

Marchesin et al.13 reported anomalies in voluntary saccade control in a wide variety of disorders such as dyslexia, learning disorders, and ADHD, thus supporting the compared data.

Our data sets seem to support the hypothesis postulated by Frank and Levinson15 in that vestibular disorders may interfere with sequential eye fixation required for reading.

These concerns have guided studies such as the one by Horak et al.16 in which the vestibular function of children with and without reading and writing disorders was analyzed. Altered vestibulo-ocular reflexes were found in 20% of the children underperforming at school. This adds to the findings reported by Hoyt14, as eye movement required for reading alternates between saccade movement and periods of fixation, thus requiring the integrity of the vestibular apparatus and of saccadic movements.

Our study showed that the mean values found in the caloric tests are within normal ranges for digital vectonystagmography as defined by Ganança et al.24 in hot thermal stimulation (42ºC), for both children underperforming at school and those doing well in class. However, values above the normal ranges defined by Ganança et al.24 were found in cold thermal stimulation (18ºC) of children underperforming at school, showing a statistically significant relationship between variables for both left and right stimulation (p= 0.031 and p=0.012 respectively).

Thermal stimulation is the most sensitive of the conventional vestibular tests. It allows the identification of vestibular disorders in patients without specific complaints and with normal results in other vestibular assessment steps.

The statement above was considered in the assumption that drove Ganança et al.11 to confirm that the caloric test is the vestibular test that presents the greatest number of alterations.

When looking at nystagmus labyrinthine or directional preponderance found in the caloric test, we observed a statistically significant association between variables when comparing children with and without learning impairment (p= 0.012). Our data sets show peripheral vestibular disorder combined with labyrinthine excitation, leading to vestibular hyperactivity.

Ganança19 studied 64 children with language disorders without complaints of dizziness and found high rates of vestibular disorders in peripheral topographic diagnosis.

When producing the diagnosis of the children enrolled in our study we found a high rate of normal vestibular test results (73.3%) among children doing well in class and lower rates (32.6%) among those with learning impairment. The identified vestibular disorders had both unilateral and bilateral irritative peripheral origins, and involved 67.4% of the children with learning impairment and 26.7% of the children performing well at school. There was a statistically significant association between variables (p= 0.001).

Our results agree with the finding reported by Ganança et al.11 when they studied 30 children complaining of learning impairment and found altered computerized nystagmography results in 20.0% of the children analyzed, all in peripheral topographic diagnosis.

Similar findings were reported by Franco and Caetanelli20. School-aged children underwent vestibular examination through vectonystagmography and 20.7% of them had both unilateral and bilateral peripheral vestibular disorders.

Sensorial stimuli are fundamental for the development of learning skills in children. When stimulated from an early age, children will develop god coordination, focus, creativity, and self-confidence, thus minimizing the chances of experiencing learning impairments.

Considering the relevance of the relationship between learning impairments and the vestibular system, further investigation must be conducted to confirm the findings reported in this study and to shed light on the ambiguities for which answers were not found.

In order for obscure aspects not to prevent proper intervention from being offered, more research and work on speech and hearing therapy is required.

Our study showed that the mean accuracy values (in the assessment of saccadic movement) and the normal value thresholds in caloric tests specially under cold thermal stimulation (18ºC) were statistically significant in children complaining of learning impairment. A statistically significant relationship was also found for vestibular disorder and children affected by learning impairment. All found vestibular disorders are of a peripheral irritative origin.